There is much art on flame-retardants, but little on smoke-retarders or suppressants. A paper entitled SMOKE GENERATION FROM THE BURNING OF SOME POLYMERIC MATERIALS BY Brauman et al, given at the 32nd Annular Technical Conference of the Society of Plastic Engineers held in San Francisco in May 1974 discusses the problem and the effect of several smoke deterrents, but does not suggest the invention. Mitchell U.S. Pat. No. 3,821,151 suggests the use of molybdenum oxide in conjunction with iron powder and copper oxide as a smoke retardant in polyvinyl chloride, but no data are given. Miscellaneous patents on smoke retardants for vinyl chloride resins include, for example, Frisch U.S. Pat. No. 3,725,319, Doerge et al U.S. Pat. Nos. 3,746,664 and 3,758,638, McRowe U.S. Pat. No. 3,819,577, McRowe U.S. Pat. No. 3,822,234, and King U.S. Pat. No. 3,900,441; but these include no suggestion of the invention.